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A Novel Approach to Minimize the number of Controls
in Defectivity Area (13th Technical Meeting of ARCSIS,
Rousset 2010)
Justin Nduhura Munga, Claude Yugma, Stéphane Dauzère-Pérès, Philippe
Vialletelle
To cite this version:
Justin Nduhura Munga, Claude Yugma, Stéphane Dauzère-Pérès, Philippe Vialletelle. A Novel Ap-proach to Minimize the number of Controls in Defectivity Area (13th Technical Meeting of ARCSIS, Rousset 2010). 2010. �emse-00605651�
A novel approach to minimize the number of controls in Defectivity area
Authors: J. Nduhura1, 2, C. Yugma1, S. Dauzère‐Pérès1, P. Vialletelle2
1 Ecole Nationale des Mines de Saint‐Étienne ‐ Centre Microélectronique de Provence ‐ Site Georges
Charpak, 880 Avenue de Mimet, F‐13541 Gardanne France ² STMicroelectronics, 850 Rue Jean Monnet, 38920 Crolles
I. Introduction
The transition from 200‐mm to 300‐mm wafers has seen the introduction of numerous controls at different stages of manufacturing in the semiconductor industry. This is because increasing the size of the wafer combined with a reduction in the size of the transistor has made more expensive the price of a wafer [1]. In this study, we investigated the case of controls in the defectivity area for the CMP (Chemical Metal Polishing) workshop and proposed a solution and a prototype which helps to highlight when too many measurements are done for “nothing” and when there is a lack of measurement. The solution proposed here is based on real time data analysis and risk computation in terms of number of wafers processed on a production tool since the last control. This notion is called Wafer At Risk [2][3]. It helps to reduce the work in the defectivity area and reorganize some activities in the fabrication line of ST Microelectronics Crolles.
II. Description of the study
The goal of this study is to master the risk of processing a lot on a tool using real time data analysis and to minimize the number of controls. It consists in sampling lots in order to minimize risks. To each lot is associated a risk array. This array contains the new value of each risk (or of the risk reduction) if the lot is measured. And when a lot is measured in the defectivity area, the risks of various tools are reduced [2] [3].
The evolution of the risks might be controlled by warning and inhibit limits. The question asked here was: how to be sure that the Inhibit limit would not be exceeded to avoid the case of lack of control and how to know and determine the right time for a measurement to avoid “unnecessary” control?
III. First results and conclusion
The algorithm, based on the idea described in the paper, has been implemented and tested on real instances of the industry. The algorithm has been embedded in a prototype. After two weeks of utilization of the prototype, a first analysis helped to highlight the major case of over‐control and lack of control.
IV. References
[1] A‐J Su, J‐C Jeng, H‐P Huang, C‐C Yu, S‐Yu Hung, C‐K Chao (2007). Control relevant issues in semiconductor manufacturing: overview with some new results. Control Engineering Practice 15 (2007) 1268‐1279
[2] S. Dauzere‐Pérès, J‐L Rouveyrol, C. Yugma, P. Vialletelle (2010). A smart sampling algorithm to minimize risk dynamically. [Accepted in Advanced Semiconductor Manufacturing Conference, San‐Francisco, USA, San Francisco, July 2010]
[3] M. Shanoun, M. Bassetto, S. Bastoini, P. Vialletelle (2010). Optimization of the process control in a semiconductor company : model and case study of defectivity sampling. International Journal of Production Research